The present application claims priority upon Japanese Patent Application No. 2001-123122 filed on Apr. 20, 2001 which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to a disk array device, and particularly relates to a technique for updating contents of firmware of a hard disk unit mounted on a disk array device without interrupting operation of the disk array device.
2. Description of the Related Art
A disk array device is a data storage for performing storage of data, which is received from a host computer such as a personal computer, an office computer, or a mainframe connected via a certain communication means such as a LAN, under high reliability and high availability by a RAID mechanism structured by the hard disk units and/or various security functions. With the recent development of IT-related industries, there is an increasing need for disk array devices in many areas as a large-capacity storage of an open system, and further as a component of a SAN (Storage Area Network) or the like such as in a data center.
FIG. 1 is a schematic block diagram of a recent, typical disk array device. The disk array device is constructed of, for example, a communication interface 11 such as a LAN for communicating with host devices 2 such as a personal computer, an office computer, or a mainframe, a CPU 12 for executing and controlling, for example, the control of various parts, the RAID mechanism, and various security functions and/or various maintenance processes of the disk array device, various memory groups 13 for example, a RAM or a ROM, a disk control circuit 14 comprising an interface circuit of such as IDE or SCSI, and a plurality of hard disk units 15 mounted in the device and connected to the disk control circuit 14.
As shown in FIG. 2, the hard disk unit 15 mounted on the disk array device is constructed by comprising, for example, a mechanical section 21 commonly known as an HDA (hard disk assembly) constructed by a spindle motor, a disk body, and a head performing reading and writing of data, and an electronic circuit section 29 referred to as a PCB (printed circuit board) mounted with various electronic circuits such as a mechanism control circuit 23 conducting various control of the mechanical section 21, a signal processing circuit 24 for performing receiving and handing of data signals to the mechanical section 21, an interface circuit 25 for connecting to an external apparatus (in this case, the disk control circuit 14), a CPU 26 for performing various control of the entire unit, a RAM 27 serves as a buffer memory and/or a cache memory, and a re-writable non-volatile memory 28 comprising for example a flash memory.
Here, the non-volatile memory 28 is recorded with the firmware for performing various control of the hard disk unit 15 such as the mechanical section and the electronic circuit section. Also, this firmware has a character of being appropriately updated for various reasons, such as, homogenizing of ability of each of the hard disk units 15 performed in aim to increase process speed and decrease error occurrence frequency when RAID is in operation, in version updating, or bug fixing.
By the way, the updating of the firmware is generally performed by a method of transmitting update data for the firmware from the disk array device to the hard disk unit 15. However generally, since the firmware is software which handles the central functions of the hard disk unit 15, during the firmware update, the function of the hard disk unit 15 must be temporarily interrupted. Further, after the update of the firmware, a so-called rebooting (resetting) process is necessary. This rebooting process (that is, from when the rebooting order was given until the hard disk unit 15 starts to operate by the new firmware) requires approximately several tens of second. Moreover, since this period of time is a length which exceeds the time-out value set in the disk array device, the operation of the disk array device is also interrupted by the rebooting operation, and in particular, the update of the firmware of the disk array device in operation will temporarily interrupt a client's business.
Thus, in order to solve the above problem, the present inventors developed a hard disk unit having a function to perform an update of firmware without interrupting a data-reading-and-writing process (hereinafter, referred to as “update-while-ON function”), and have already produced a disk array device which may perform firmware updating without interrupting the operation of the disk array device by structuring all the hard disk units to be mounted with the hard disk units having the update-while-ON function.
However, the number of disk array devices having such a function is still few at present. Further, from various reasons such as problems in design, in view of production, and in regarding cost, disk array devices comprising hard disk units 15 not having the update-while-ON function are thought to be continually utilized hereafter in many circumstances and places. Thus, the development of a mechanism, which updates firmware without interrupting operation of a disk array device even without the update-while-ON function, is still expected.